What makes us human?How did we develop language, thought and culture?Why did we survive, and other human species fail?

The past 12,000 years represent the only time in the sweep of human history when there has been only one human species. How did this extraordinary proliferation of species come about - and then go extinct? And why did we emerge such intellectual giants? The tale of our origins has inevitably been told through the 'stones and bones' of the archaeological record, yet Robin Dunbar shows it was our social and cognitive changes rather than our physical development which truly made us distinct from other species.

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Review

Human Evolution is a must-read. It has the great strength of showing you the inner workings of an imaginative mind, while allowing you the freedom to think (New Scientist)

About the Author

Robin Dunbar is an evolutionary psychologist and former director of the Institute of Cognitive and Evolutionary Anthropology at Oxford University. His acclaimed books include How Many Friends Does One Person Need? and Grooming, Gossip and the Evolution of Language, described by Malcolm Gladwell as 'a marvellous work of popular science.'

Top customer reviews

A wonderfully lucid and analytical approach to human evolution. Dunbar's proposed correlation between brain development and social group size (measured partly by number of Facebook friends and size of Christmas card lists!) and his time budget analysis of the reasons for the extinction of other 'hominin' species is both entertaining and enlightening. I loved it.

As a bibliophilic teenager, at least once a week I would make the pilgrimage downtown to Clulow’s, a sadly long-defunct independent bookshop, where I would enjoy browsing the Orange-, Grey- and Black-edged Penguins and iconic blue-edged Pelicans. At home my incipient book collection began to emulate the colour-scheme, allowing only the rarest glimpse of a white-edged Picador or randomly hued Panther. From those books I began my exploration of world literature and learned my first proper lessons in Greek and Roman history and mythology, philosophy, psychology, politics, economics and linguistics.

Some of those books continue to adorn my bookshelves, remaining as a reminder of an autodidactic past. It was therefore something of a thrill to find that the Pelican imprint was being relaunched.

Elsewhere I review the first product of this initiative, Ha-Joon Chang’s introduction to economics, which is excellent but, having just completed an economics degree I had a more informed and specialist view of its content, not to mention its overtendency to reference popular culture. Thus reading that book was a different proposition from the second, Robin Dunbar’s introduction to Human Evolution, a subject in which my prior knowledge was relatively shallow, but which manages to avoid, for example, references to Star Trek when explaining symbionts.

So it was that I began my transformation from casual to dedicated observer of people in groups, as that is essentially what for me is the greatest takeaway from Dunbar’s book. In the Financial Times Gillian Tett, an anthropologist by training, cited Dunbar’s revelation that on average the approximate human bonded-group size is 150, speculating on the implications of that for the way we live and, for that matter, the people on Facebook who claim to have thousands of “friends”. (Lower intimacy groups of 500, acquaintances, and 1500, tribes, are also covered, however.)

But the revelations that most interested me were those regarding the role of social grooming in releasing endorphins in the primate body, thus providing the pleasure associated with socialising, and the role language plays in increasing human efficiency in social grooming by doing away with the need continually to comb each other’s hair in pairs by permitting multi-tasking, engaging in social grooming by talking with each other as we hunt, travel and create.

One of the studies Dunbar cites involved the size of groups in pubs. Here the average size of a social group, a set of people who are obviously together is, apparently seven. But when it comes to a conversation group, where one or more people talk whilst the others listen, the average size is four, and laughter groups, in which people talk and occasionally laugh together is three. The efficiency in this arrangement is that unlike social grooming of the hair-combing variety, the release of endorphins occurs in both giver and receiver, not just the receiver, hence three people are groomed simultaneously.

The numbers cited are what have had me paying more attention lately to groups of people in public places. Thus should you find yourself aware of some weirdo paying an unusual amount of attention to your small gathering in a public place, it may be me, seeing if you’re tuning out as the fourth member of your group relates an amusing tale.

(Incidentally, who knew that it was possible to get paid for sitting around in pubs watching people chat? Why wasn’t I told earlier? But more seriously, I did also wonder if pubs are the best places to run this kind of study, and what the results may have been in, say, a works canteen or sports centre.)

Dunbar begins his study by outlining the questions he is setting out to address and the two essential tools he will be using, the social brain hypothesis and the time budget models. He explains the differences between hominins and hominids, why the great apes are unable to live far from the equator, details the five transitions in human evolution that have brought us to where we now are, and explores potential explanations for how language, fire and cooking allowed our precursors to travel, organise and develop sophisticated modes of reasoning and expression, eventually becoming Anatomically Modern Humans. He also explores the potential reasons why Neanderthals, contrary to popular myth highly evolved and intelligent, nevertheless became extinct whilst homo sapiens survived and thrived.

What becomes apparent as Dunbar progresses is that, far from there being a missing link, there is a remarkable amount of contiguous evidence available for us from which to construct a history of human evolution, much of which extends beyond theory into what Richard Dawkins calls “theorem”. We will never know the precise date when the first word was spoken, nor what it was, or the location or source of the first artificial fire, but we do know enough to say when brains and physiologies, and behaviour and diet had developed sufficiently for these things to be potentially possible. Fire, for example, as well as extending the length of the day beyond nightfall, improved the efficiency of eating, rendering meat both more digestible and more nutritious, reducing the quantity of food required to survive and the amount of time required for acquiring and eating it, thereby freeing up more time for socialising and creating the things that ultimately make us human, including religion and art.

Later, as human groups expanded, came the development of culture, freeriding and the appearance of pair-bonding. On this latter Dunbar is almost clinically analytical, dissecting the several possible reasons why pair-bonding came about, and examining the ways in which the pair-bond breaks down along with potential reasons, including the presence of a philandering gene in some people. I’m not sure, though, that reference to this is going to help next time you’re caught by your partner indulging in extra-curricular activities.

The book therefore gives myriad insights into what we are, where we came from, and why we do some of the things we do, making the routine of everyday living a source of interest. Evidence of learning is sometimes said to be a change in behaviour. Clearly I’ve learned.

I only have one quibble. On a couple of occasions the word “design” creeps in in places where more care is needed, as with a footnote which describes human feet as “designed” to allow a striding form of motion. Strictly speaking they “evolved” that way; using the word “designed” runs the risk of further confusing those folks who believe the world is only 6000 years old. There are also a couple of occasions where Dunbar seems to be over-enjoying the flaws in some other people’s theories, rather than just, as he does when he’s most convincing, surgically assessing the weaknesses in their assumptions and conclusions.

If you have ever watched tv progams about the evolution of apes into man, this book fills in the gaps that a 1 hour tv program inevitably leaves. It explains the speciation of various lineages of ancient apes into other specias and eventually the last common ancestor which split from a separate lineage, then evolving into us. It makes sense of the image you often see on t-shirts of a primate evolving an increasingly erect posture. It also talks about the evolution of the various species of hominin from the last common ancestor through to australopithacus and onto the various homo species, explaining how the brain grew and the development of culture, family, childhood and diet heled the homo species survive and what made homo sapiens the most successful homin species. excellent reading.

Have read several books on human evolution but this is the first that goes on about time budget models. Struggled with some sections but it was worth sticking with it until the end. Less about the fossils and more about time allocation. I am now able to consider my own 'time budgets' as I whistle through life, eating, sleeping and reading. This is the second Pelican introduction I have read and I will now be moving on to another.

The title of this book is misleading. The book is about two models Dunbar devised (a 'time budget model' together with 'the social brain hypothesis'), and their application to human evolution. It is not a summary of human evolution itself, but more a discussion of the application of the chosen models.

The models themselves are interesting (especially the social brain hypothesis), and I found the introductory chapters which set out the models fascinating. I even made a list of all my friends to see if the number came to 150 (it did).

Dunbar comes up with a simple set of mathematical equations (the inputs seem to be brain size; time taken feeding, travelling and grooming; type of food available) and we can then reconstruct every stage of human evolution with precision. Or can we?

Illuminating though the models are, Dunbar goes off the rails in the attempt to apply these to situations millions of years ago. He needs to make heroic assumptions at every stage, and over reliance on his cherished models to the exclusion of other factors blinkers him.

The idea that a complex system, (such as the interaction of a hominin species with its environment) can be reduced to a few equations with minimal inputs is really rather silly. The great difficulties economists have in analysing contemporary human systems shows the extent of the challenge - and the economists are here to observe what's going on in minute detail.

There is a danger of applying mathematical modelling to complex systems - it can give the user a false sense of security and a fair degree of over confidence. The author does not seem to be aware of these limitations.

Dunbar exhibits what I would call a strongly male brain. He evidently feels the urge to put everything into tidy boxes that can be summed up in a few elegantly simple equations. But real life is not like that.

That is not to say that there is nothing of interest to be gleaned from applying Dunbar's models. But these models on their own cannot provide anything definitive, and I am surprised that a book with such a narrow viewpoint is being marketed as a general introduction.